1. FIELD OF THE INVENTION
This invention relates to an improved electrical contact construction for an electrical switching apparatus of the type in which a contact overlay is soldered to a contact carrier.
2. DESCRIPTION OF THE PRIOR ART
Electrical contacts of the above-described type are generally known in the art. Generally speaking, when the parts of such contacts are soldered together, faults are produced between the contact carrier and the contact overlay, especially if the solder utilized is continuously supplied. Such faults can be reduced in number by inserting prefabricated (for example, rolled) solder layers between the contact carrier and the contact overlay prior to soldering, but such a solution is relatively expensive. Moreover, the contact carrier and the contact overlay of the contact can be soldered together with continuously supplied solder only for small gap depths, e.g., two to three millimeters. Otherwise, a satisfactory degree of filling is not obtained. If solder joints of a large area are filled either by manually supplying the solder or by applying preformed solder parts from the outside, poor filling, and faults, result. This occurs, since at the beginning of the soldering process, the solder penetrates uniformly into the work piece. As the soldering progresses, however, the soldering front lags in the interior of the solder joint. In the final stages of the process, the solder reaches at the lateral edges thereof the edges of the contact overlay which are to be soldered to the carrier, and then flows along the edges of the overlay and closes the solder gap. Flux which remains in the interior of the solder joint then cannot escape to the outside of the joint, and accordingly forms a major occlusion. This adversely affects the strength of the solder joint, and in electrical contacts, results in increased burn-off losses due to arc stabilization.